Maintenance of railroad cars sometimes requires lifting or elevating the car frame to increase the clearance between the frame and the rails. Such lifting may be required, for example, to replace or repair complete trucks or wheel and axle sets.
A jack assembly for railroad cars is shown in U.S. Pat. No. 4,805,875. That patent discusses the requirements of a railroad car jack and the general nature of the prior art and problems therewith. The jack of the '875 patent has a compact power lift cylinder, in the form of a multiple-sleeve power cylinder which is engageable with the center sill or beam of the car frame.
While the jack of the '875 patent is suitable for cars having a center beam or sill, it is not adapted for use with well cars. Well cars have two side beams or sills which define a well for carrying containers. The side sills are connected at their ends to end sills which in turn are supported on trucks. The well is defined between the trucks. To permit carrying stacked containers, the well has a low clearance above the tracks. The clearance under the bottom of the sills in a well car is approximately six inches.
Well cars may be either standalone cars which have a single platform or section with trucks and couplers at each end. Or the well car may have a plurality of platforms or sections joined at shared, articulated trucks with couplers only at the outer ends. In either configuration, the structure of a well car presents lifting problems not addressed by the jack of the '875 patent.